I am am sorry Meeko has this trouble.
Bless you for taking such awesome care of him to get him to 18!
Leaning against the wall can indicate a visual issue or dizziness.
He may have an ear infection that is causing a vestibular problem.
Read more here:
He could also have high blood pressure, diabetes, hyperthyroid, renal issues, or have injured himself.
Eating is a good sign that he is not feeling too bad.
However, if he gets any worse or stops eating it is best to have him seen.
Please let me know how he is doing.
Please be so kind as to rate my answer with positive feedback; that is the only way I receive credit for my assistance. Thank you very much!
Providing a positive rating will not end our conversation, should you need me for any follow-up. Simply click 'Reply' for clarification or additional information, if needed, at no additional charge.